Vehicle drive devices that include an oil supply portion capable of supplying both oil discharged from the first pump and oil discharged from the second pump to at least a speed change mechanism are known as such a vehicle drive device. For example, Japanese Patent Application Publication No. 2009-52638 (JP 2009-52638 A) (Patent Document 1) discloses a configuration that includes an oil supply portion [hydraulic oil supply device] having a first oil passage [suction passage 17] in which oil to be supplied to the first pump [first oil pump 11] flows and a second oil passage which branches off from the first oil passage and in which oil to be supplied to the second pump [second oil pump 12] flows. This oil supply portion is capable of supplying both oil discharged from the first pump and oil discharged from the second pump to the speed change mechanism [automatic transmission] via a hydraulic control device [hydraulic circuit 20].
The oil supply portion of Patent Document 1 includes an electromagnetic switch valve that switches the relation of connection of the first pump and the second pump between an oil pan and the hydraulic control device to parallel connection or series connection. By switching the position of the electromagnetic switch valve so that the two pumps are connected in parallel, the control device can supply oil discharged from the second pump driven by an electric motor to the hydraulic control device even if driving of the first pump is stopped upon, e.g., idling stop.
If a long time has elapsed since a main power supply of the vehicle was turned off, it is more likely that oil in the oil passages (the first oil passage and the second oil passage) in which oil to be supplied to each pump flows has been returned to the oil pan by its own weight and has been replaced with air. If the main power supply of the vehicle is turned on in this state and the second pump is driven, an oil pressure does not actually start to be generated until the air present in the oil passages has been discharged. Accordingly, oil may be late in being supplied to the speed change mechanism. For example, this problem tends to occur particularly when the oil temperature is low in winter etc., because viscosity resistance of oil is increased. If the oil temperature is lower than a predetermined temperature when the main power supply of the vehicle is turned on, the control device of Patent Document 1 switches the position of the electromagnetic switch valve so that the two pumps are connected in series. Thus, oil discharged from the first pump having higher discharge capability is supplied to the second pump via the electromagnetic switch valve so as to forcibly circulate the low temperature oil in the second pump. Accordingly, oil can be promptly supplied to the speed change mechanism without using a rotating electrical machine having a large physical size as a power source that drives the second pump.
In the technique of Patent Document 1, however, torque of an internal combustion engine needs to be increased so that the second pump can be forcibly driven by the first pump, which reduces fuel economy. Moreover, since the electromagnetic switch valve is required, the cost and size of the vehicle drive device are increased accordingly. Patent Document 1 therefore cannot make good use of advantages that the fuel economy is improved by driving the second pump and that a rotating electrical machine having a relatively small physical size can be used as the power source that drives the second pump.